1. Field of the Invention
This invention relates to a device for observing the processes taking place in the combustion chamber of an internal combustion engine during operation through one or more observation openings or bores located in a wall of the combustion chamber.
2. Description of the Prior Art
In order to enable combustion processes in the combustion chamber of an internal combustion engine to be photographed with cameras for high-speed cinematography, various types of engines have already been built with this aim in mind. The addition of the high-speed cinematography equipment necessitated a number of modifications in these engines, however, as compared with the commercially available engines, causing drastic changes of essential engine parameters, e.g., flow characteristics, thermodynamic state, geometry of the combustion chamber, etc.
For example, a diesel engine was provided with a cover of quartz or plexiglass through which the combustion chamber was filmed during the process of combustion with the use of a mirror. As the transparent cylinder head would not permit the addition of valves, a port control system had to be used, which resulted in completely different flow conditions in the combustion chamber as compared with valve-controlled engines.
In another variant of such an observation device a piston with a transparent head was used through which the combustion process may be filmed via mirrors projecting into open slits in the piston jacket. Since the mirrors had to remain clean, the use of an oil-lubricating system was prohibited. For sealing purposes teflon rings had to be used, allowing only speeds of up to 1,500 revolutions per minute.
In both of these known variants the soiled transparent components had to be cleaned after as few as 10-20 working cycles.